Conversion of alkenes to ketones can be conventionally accomplished by ozonolysis or by Tsuji-Wacker oxidation. Such conversion processes can be useful in a wide variety of industrial and synthetic chemistry applications as solvents, intermediates, or the like. In particular, Tsuji-Wacker oxidation, which is a palladium-catalyzed conversion of a terminal olefin to a methyl ketone, has widespread synthetic applications, owing to an extensive substrate scope and the orthogonal reactivity of olefins and ketones. However, a major limitation in the scope for Wacker oxidation chemistry is for allylic alcohols and their protected variants. Oxidation of theses substrates yields a high utility acyloin product, which is an attractive synthon for asymmetric synthesis. However, previous reports of Wacker oxidations on protected allylic alcohols using Tsuji-type conditions found diminished selectivity for the desired methyl ketone and frequently yielded 1:1 formation of the corresponding aldehyde.
The current approach to accessing the methyl ketone products from allylic alcohols is a two-step procedure, which generally utilizes stoichiometric amounts of mercury, palladium, and copper. Although this method allows for access to acyloin products in good yields, the method also results in high metal loadings and toxic byproducts. Therefore, existing techniques have limitations which reduce their desirability in commercial use.